Do high-resource areas play a large role in insect predation in Iowa crop fields?

Iowa agriculture is dominated by annual production of row crops grown in monocultures. While conventional management helps Iowa lead the nation in corn and soybean production, these approaches include frequent environmental disturbances that reduce biodiversity and, in turn, decrease the delivery of ecosystem services. Non-cropped features adjacent to a crop field conserve biodiversity, especially predators of insects and weeds like ground beetles (Order: Coleoptera; Family Carabidae). Prairie strips are a recent conservation practice that produces small patches of perennial vegetation within and around crop fields. In 2022, we conducted a study at one field in Iowa to measure how the ground beetle community correlated with insect predation in the adjacent crop. We measured the community using pitfall traps (n=42) and predation using European corn borer (Ostrinia nubilalis; Lepidoptera: Crambidae) as sentinel prey placed at three distances (5, 15, and 30m) from a non-cropped feature (prairie strip or grassed waterway). We also measured these parameters in the cropped area far from these non-cropped features (45m away). We hypothesized that the most beetles and highest predation rates would be observed closest to prairie strips. Contrary to our prediction, predation was greatest and most explained by carabid activity furthest from the prairie strips. Our current hypothesis is that beetles farthest from the prairie strips are resource-limited, resulting in increased activity and increased sentinel prey consumption. This study will be conducted again in 2023, expanding to multiple fields with prairie strips, to determine the level of consistency in response.